In electronic systems, mixed-signal circuitry uses both analog and digital electrical signals to accomplish certain tasks. Often in these types of systems, it is necessary to convert from one type of signal to another, such as from an analog signal to a digital signal. For example, an analog electrical signal from a sensor may require conversion into a digital electrical signal to be properly analyzed or processed by a digital processor.
Analog-to-digital converters (ADCs) are commonly used to convert continuous analog signals to discrete digital values. Analog-to-digital converters are often configured to compare the voltage of an input signal to a number of reference voltages to determine which reference voltage is closest to the value of the input. A digital representation of the input signal is then created based on a series of such voltage comparisons.
In some alternative arrangements, an ADC may be configured to operate in terms of current. In other words, the current of an input signal may be compared to a set of current references to determine which reference current is closest to the input current. A digital representation of the input signal is then created based on a series of such current comparisons.
Throughout the drawings, identical reference numbers designate similar, but not necessarily identical, elements.